Today, there are numerous situations in which confirming the type of vehicle passing over a spot on the road is important. While visual inspections can provide a good deal of information, they do not readily report the magnetic signature of a vehicle, which can reveal additional details about the vehicle contents. Methods are needed for determining that magnetic signature in a cost effective and reliable manner.
The situation has some significant hurdles. Running wires to sensors embedded in roadways turns out to be difficult, expensive, and often unreliable in the rugged environment of a roadway with multiple ton vehicles rolling over everything on a frequent basis. What is needed is a way to use a wireless vehicular sensor node to report something approximating the raw vehicular sensor waveform via wireless communications.
Wireless vehicular sensor networks often use repeaters and/or some of the vehicular sensor nodes to wirelessly convey wireless messages from distant sensor nodes to where they are collected, which will be referred to herein as intermediate nodes. These intermediate nodes are usually essentially invisible to the network, but add a significant delay to the time from the sending of the messages, and their reception at the collection node. Additionally, a wireless vehicular sensor network may not provide a ready mechanism to time synchronizing these messages, making it difficult form an accurate picture of the magnetic signatures of the sensor state of these systems taken as a whole. What is needed are methods and mechanisms supporting the time synchronization of these reports which allows a view of the system state at a given moment to be assembled.